The invention relates to fuel rails for internal combustion engines, and more particularly to a fuel rail damper to reduce pressure pulsations in the fuel rail.
Fuel injection systems for automotive, internal combustion engines may use a number of fuel injectors, each of which delivers fuel to the inlet port of an engine combustion chamber. In some of these systems, the fuel injectors are mounted in sockets in a common fuel rail which supplies fuel to each of the injectors. The fuel rail simplifies installation of the fuel injectors and equalizes the delivery of fuel to the injectors.
When electromagnetic fuel injectors are used, the injectors deliver fuel to the engine in metered pulses which are timed to control the amount of fuel delivered and to coordinate the fuel delivery with the operation of the engine. The sequential activation of the fuel injectors coupled with low compliance in the fuel system results in pressure pulsations within the fuel rail which can result in fuel line pressure pulsations which inhibit the accurate delivery of fuel. More specifically, the variations in differential pressure across the injectors causes a variation of the amount of fuel that flows through each injector during the period in which it is open.
Dampers located external to the fuel rail have been used, but these dampers require additional space and are often difficult to locate and service. U.S. Pat. No. 5,617,827 issued to Eshleman et al. discloses a damper located within a fuel rail. The damper has two mated shells enclosing an air pocket, with the mated shells forming a peripheral flange that permits the damper to be secured and supported at both of the fuel rail ends by damper supports. However, the damper and damper supports add a level of complexity to the system that both increases costs and reduces accessibility to the fuel rail interior.
It is therefore an object of the present invention to provide a simpler and lower cost fuel rail damper that effectively reduces noise in the fuel rail. It is a further object of the invention to provide a damper that can be easily re-charged or replaced, and which can be used to monitor pressure conditions within the fuel rail.